Storage systems, or autochangers, are commonly used to store data cartridges at known locations and to retrieve the desired data cartridges so that data may be written to and/or read from the data cartridges. Accordingly, large volumes of computer-readable data can be stored on numerous data cartridges and accessed by one or more computers connected to the storage system (e.g., over a network).
Such storage systems may include one or more storage magazines and cartridge read/write devices. The storage magazines serve as a storage location for the data cartridges, and the read/write device(s) provide access to the data stored on the data cartridges. The storage system may also include a controller operatively associated with a picker assembly as well as a drive system for moving the picker assembly among the data cartridges stored in the storage system.
As an illustration, if the controller receives an instruction to access a certain data cartridge, the controller causes the drive system to move the picker assembly to the location of the desired data cartridge. Then, the picker assembly retrieves the data cartridge and delivers it to the read/write device. The picker assembly may also be operated to return the data cartridge to the storage magazine following the read/write operation.
Typical data cartridges have relatively slow access times. For example, once the data cartridge has been delivered to the read/write device, it may take another 4 to 6 minutes to position the read/write head before the read/write operation can begin. Hard disk drives have much faster access times. For example, positioning the read/write head provided with a typical hard disk drive may take only about 10 to 15 ms before the read/write operation can begin.
Until recently, hard disk drives have generally been more expensive than data cartridges. But recently, the cost of hard disk drives is approaching the cost of data cartridges, and therefore hard disk drives are becoming more common for mass storage solutions than they have been in the past. For example, hard disk drives are typically provided for RAID (i.e., random array of independent disks) storage systems.
The hard disk drives used in RAID storage systems are always connected, even when not in use. Hard disk drives provided in an “always-connected” system are subject to wear and tear (e.g., from heat) or even permanent damage or data loss (e.g., during a power surge). In addition, extensive cabling is required to link each of the hard disk drives in such a system.